1. Field of the Present Invention
The present invention relates generally to externally mounted rearview mirrors for vehicles such as tractor-trailer combinations. More particularly, the invention relates to a device for automatically controlling the position of a movably mounted mirror in response to an angular relationship between the vehicle and the trailer being towed by the vehicle.
2. Description of the Prior Art
The maneuvering ability of articulated vehicles, particularly tractor-trailer combinations, is often hampered by the difficulty in quickly and conveniently determining the location of the rear end of the trailer. This difficulty is substantially increased when the trailer is long and turns toward the right side of the vehicle while the turn is being negotiated. Typically, the externally mounted rear view mirrors are positioned for straight ahead driving, and thus, a right handed turn during backing of the vehicle causes the right hand mirror to reflect an image of the side of the trailer and the left hand mirror would be directed outwardly away from the trailer. Similarly, when a left hand turn is being negotiated while the vehicle is being backed up, the left hand mirror is directed against the side of the trailer and the right hand mirror reflects an image outwardly away from the trailer.
Although the driver of a left-handed drive vehicle can view the left rear end of the trailer by peering out the left hand window, when the trailer is turning toward the left, the driver must turn his head an divert his attention away from the front of the vehicle. Moreover, the driver's peripheral vision may not provide immediate perception of events occuring at the front of the vehicle. Moreover, the driver is unable to peer out the right hand window and view the right rear end of the trailer when a right hand turn is being negotiated.
In view of these problems, mirrors have been made to move in response to the orientation of the trailer relative to the vehicle such that the field of view through the mirrors is changed while the turn is being negotiated. Some previously known devices for moving mirrors have been connected to the steering mechanism of a vehicle. Nevertheless, since the rear end of the trailer does not follow the exact route of the steered wheels of the vehicle, the image provided by such a mirror actuating device can often be displaced from the rear end of the trailer.
Another previously known actuating device moves the mirror in response to angular orientation of the trailer with respect to the vehicle. A previously known actuating device of this type is disclosed in U.S. Pat. No. 3,950,080. This patent discloses a mechancial actuating device for automatically changing the orientation of side view mirrors in response to the angular relationship between the trailer and the vehicle at the pivot connection between them. One disadvantage of this previous system is that the longitudinally sliding plates, which provide direct displacement of a mirror actuator, and the pivot mechanism are exposed to environmental conditions which can effect the operation and useful life of the moving parts. Moreover, repeated repair or replacement of the components may be necessary due to the large forces and stresses exerted on the parts, and the forces may also contribute to misalignment of the parts after repeated use.